"With four more bodies found, including that of a 12-year-old girl, the number of dead has gone up to 25," Patna District Magistrate Sanjay Agrawal told the media.
Pritay Amrit, the Principal Secretary in the Disaster Management wing, said the rescue and search operation would continue on Sunday.
According to witnesses, the overcrowded boat was returning from a kite flying festival, organised as part of Makar Sankranti by the Bihar Tourism Department, when the incident took place around 6 p.m. on Saturday.
According to officials, 25 victims have been identified, including five children and women each and 15 men.
The capsized and broken boat was taken out of the Ganga river by a team of the State Disaster Response Force (SDRF) on Sunday.
Assisting the SDRF are personnel from the National Disaster Response Force (NDRF).
A case has been lodged against the boatman and manager of an amusement park.
The rescue and search operations were halted on Saturday night in view of darkness and cold weather and resumed on Sunday.
Nearly 20 people have been rescued so far. Most are being treated at the Patna Medical College and Hospital.
Bihar Chief Minister Nitish Kumar has ordered a probe into the tragedy.
The government has announced an ex-gratia of Rs 4 lakh to the next of kin of each victim.
Bihar's ruling Janata Dal-United cancelled its feast on Sunday to mark Makar Sankranti festival in view of the tragedy.
Patna boat tragedy: PM announces ex gratia of Rs 2 lakh
Prime Minister Narendra Modi today sanctioned Rs 2 lakh each to the next of kin of those killed in Patna boat tragedy from the PM National Relief Fund.
Those seriously injured will be given Rs 50,000 each, the PMO said.
Last night, while condoling loss of lives, the PM has postponed his programme scheduled for today in Patna.
"PM expressed grief on the loss of lives caused by the boat tragedy in Bihar. He extended condolences to the bereaved families," the Prime Minister's Office tweeted last night.
In the wake of the tragedy, a programme to mark the start of redevelopment work of Mahatma Gandhi Setu in Patna which he was to address today via video conferencing was also postponed, the PMO said.
At least 20 people, including some minors, drowned when a boat capsized on the Ganga in Patna, suspectedly because of overloading.